1. Field of the Invention
The present invention relates to a liquid crystal display panel and repairing method thereof, and more particularly, to a method able to repair bright dot defect or other pixel defect problem in an array substrate of a liquid crystal display panel.
2. Description of the Prior Art
A conventional liquid crystal display (LCD) panel normally includes a thin film transistor array substrate (array substrate), a color filter substrate (CF substrate) having a common electrode thereon disposed over the array substrate, and a liquid crystal layer interposed there between. Please refer to FIGS. 1-2. FIGS. 1-2 are schematic diagrams illustrating an array substrate of a conventional LCD panel, where FIG. 1 is a top view of a portion of the array substrate, and FIG. 2 is a cross-sectional view of the array substrate shown in FIG. 1 along the line PP′. As shown in FIG. 1-2, the conventional array substrate 10 includes a plurality of scan lines 12, a plurality of data lines 14, a plurality of pixel regions 16 defined by the scan lines 12 and the data lines 14, and a plurality of common lines 20 arranged in alternately with the scan lines 12. Each pixel region 16 has at least a thin film transistor 18 and a pixel electrode 22 corresponding to the thin film transistor 18. The pixel electrode 22 is disposed facing the common electrode of the CF substrate (not shown), in which the liquid crystal is interposed between the pixel electrode 22 and the common electrode. In addition, the overlapping region of the pixel electrode 22 and the common line 20 form a storage capacitor on common line (Cst on common). Each thin film transistor 18 serves as a switch in each pixel region 16. In the displaying operation, the common electrode of the CF substrate is usually receiving a common voltage. Following, a particular pixel region is selected through a corresponding scan line 12 receiving a scan signal and then the pixel electrode 22 of the pixel region 16 is written into a pixel voltage via a corresponding data line 14 receiving a data signal. Sequentially, the voltage difference between the pixel electrode 16 and common electrode makes the liquid crystal rotate to a predetermined direction to control the illumination out from the CF substrate and then a display is achieved.
The storage capacitor assists the pixel region 16 to operate normally, however, any processing defects or particles occurring in the storage capacitor may lead to malfunction of the storage capacitor. For instance, if a particle 24 unexpectedly falls into the storage capacitor region, the particle 24 may lead to a short-circuitry between the pixel electrode 22 and the common line 20. In such a case, the voltage of the pixel electrode 22 will be identical to the voltage of the common line 20. Since the common line 20 and the common electrode of the CF substrate usually have the same voltage, the voltage of the pixel electrode 22 and the voltage of the common electrode of the CF substrate will be identical. This fails the pixel region 16. Furthermore, if the LCD is a normally white (NW) type LCD, back light will pass through the liquid crystal layer and cause a bright dot defect because no voltage difference exists between the pixel electrode 22 and the common electrode. In addition to the particles, other defects such as a dielectric layer loss or a common line loss that makes the pixel electrode 22 and the common line 20 short-circuited will also cause the bright dot defect in an NW type LCD.
Accordingly, there is a need to provide a simply and effective repairing method of the pixel to solve the display problems due to particles or other defects.